Internal-combustion engine



March 22, 1949. I J. H. ROTHENBERGER 2,465,270

INTERNAL-COMBUSTION ENGINE Filed Nov. 20,1947 2 Sheets-Sheet 1 Mamh 1949. J. H. ROTHENBERGER ,465,270

. INTERNAL-COMBUSTION ENGINE Filed Nov. 20, ,1947 2 Sheets-Sheet 2 [NVENTO/Z U. H. RQTHEN BERGER Patented Mar. 22,1949

UNlTED STATES PATENT orrlcs 2,465,270 INTERNAL-COMBUSTION ENGINE James H. Rothenberger, Minneapolis, Minn. Application November 20, 1947, Serial No. 787,071

3 Claims.

This invention relates to a two-stroke cycle gasoline engine.

An object of this invention is the provision of such an engine having greatly increased volumetric emciency.

Another object is to provide a two-stroke internal combustion engine with an outside pump and carburetor for furnishing a combustible mixture to the cylinder, thereby making it possible to dispense with crank-case compression and to use the crank-case for splash lubrication of the cylinder.

These and other objects as will hereinafter appear are accomplished by this invention which is fully described in the following specification and shown in the accompanying drawings in which Figure 1 is a vertical section partly in elevation on the broken line I-I of Fig. 4 showing an engine.

Fig. 2 is a partial horizontal section on the line 2-2 of Fig. 1 showing a reed valve on the air p p;

Fig. 3 is a partial side elevation of this same valve; and

Fig. 4 is a partial vertical longitudinal section on the line 0 of Fig. 1.

The embodiment illustrated comprises a crank case I0, a cylinder I2 suitably secured thereto as by means of studs and nuts N, a piston I6 slidable on the cylinder and having a piston pin I0 journaled in the upper end of the connecting rod 20, the lower end of which is journaled on a crank pin 22, one end 20 of which is reduced in size and snugly fitted into an opening 26 in a crank cheek 28 which is carried on a short shaft 30 which is suitably journaled in the crankcase I0, as shown in Fig. 4. x

The crank pin 22 is firmly carried by the opposing crank cheek 38 which in turn'is firmly secured on the drive shaft 40 which is coaxial with the shaft 30. The shaft 00 is journaled in a circular closure plate 02 which is large enough to permit the crank cheeks 28 and 38 to be inserted into the crank-case from the righthand side, as shown in Fig. 4. This closure plate is secured to the crank-case ill by means of capscrews or the like 05.

The stub shaft 30 has a tapered outer end on which is secured a flywheel 50by means of a key and a nut 52. Within the flywheel is housed the magneto which comprises a fixed magnet 50 z coils 58. This magneto is not shown in detail for the reason that is well known and forms no part of the present invention. The stator 55 and coils 58 are carried by an arm 60 which also carries the primary breaker points 62 which operate on suitable notches 64 in the shaft 30. The arm 60 can be .moved about the axis of the shaft 30 for advancing and retarding the spark.

Splash lubrication is obtained by means of a finger 10 which dips into the splash pan I2 at each revolution carrying some of the oil through the spout I4 to the cylinder. The bottom of this pan is supplied with holes I6 through which oil flows up into the splash pan and the splash pan is suitablysupported within the crank-case.

The cylinder is provided with inlet and exhaust ports and 82, respectively, which are preferably of substantially the same size. The exhaust port preferably communicates with a suitable mufller 84. The inlet port communicates with a short inlet passage 86 which will be closed during the exhaust by a poppet valve 88 serving to close a valve seat 90 by means of pressure admitted to the back of the valve when the latter is uncovered by the piston in its down stroke.

The pump mechanism providing pressure at the inlet passage 06 will now be described. An eccentric 9d keyed on the shaft 40 carries an eccentric strap 96 which is pivotally connected to a pin 98 sliclable in a suitable bushing in a boss I00 which is formed integral with one side I02 of an air pump, the boss I00 extending through an oil-tight boss in the side of the crank-case I0, the side I02 being secured to the crank-case by capscrews, not shown. The other side I00 of the air pump, as well as the side I02, are formed with meeting flanges secured together with bolts, not shown, so as to grip the periphery of a flexible diaphragm I06 which may be made of a suitable fabric impregnated with an oil resistant rubber substitute such as neoprene so that it will not be injured by the presence of oil or gasoline. The spaced sides I02, I04 are oppositely dished to provide a central space I08. Disks H6, H2 are located on opposite sides of the center of the diaphragm I06 and are secured at the center on the shouldered outer end of the pin 90 by means of a nut or capscrew H0.

The sides I02, I04 of the air pump are provided with similar inlet and outlet exhaust ports which are covered by means of reed valves shown particularly in Figs. 2 and 3. These show one of the inlet ports II'G of the side I02. This is normally covered by a reed valve II8 firmly secured at the end I20. Thus the movement of the diaphragm in one direction by the pin 03 will cause air to be drawn in through the inlet ports 3, and movement of the diaphragm in the opposite direction will force the air out through the opposite outlet port I22 past its corresponding reed valve I24. It will be noted that while two of the inlet ports H are shown in the sides I02, I04, only one of the outlet ports I22 and its corresponding reed valve I24 is shown in the side I02, the upper portion of the side I04 with its outlet port not being shown in section. It is, however, a duplicate of the outlet port I22.

These outlet ports empty the air which they have compressed to approximately five pounds gauge pressure into a pressure chamber I30 which is bifurcated and tightly secured to the two sides of the air pump, as by means of screws not shown. The upper portion of this pressure chamber is necked in to form a venturi I32 with a, screwoperated needle valve I34 located in the venturi to serve as a super-atmospheric carburetor. Gasoline is introduced from a suitable tank through a pipe I35.

The needle valve I34 carrying a screw to vary its feed is operated by a valve lever I40 which is operably connected through means not shown with a fly-ball governor I42 on shaft 40. This construction is not shown in detail as it forms no part of the present invention.

The operation of this engine is as follows; with I the engine operating normally, the diaphragm I03 '88 to close so as to trap the unburned air in the pressure chamber I32. As the piston continues to descend, the ports 80 and 82 will be uncovered by the piston thereby causing the engine to exhaust through the port 82. This, plus the closure of the valve 88, causes the pressure in the cylinder to fall below that of the atmosphere due to the inertia of the moving gases. This sudden drop of pressure in the cylinder, plus the pressure already existing in the pressure chamber I 30, will cause the valve 88 to suddenly open to the position shown in Fig. 1. The air so contained in the pressure chamber I30 will then rush past the carburetor jet I34 thereby picking up a charge of gasoline and carrying it into the engine cylinder as a volatile carburetted mixture, at the same time serving to. scavenge much of what is left of the burned gases remaining in the cylinder. The passage 86 is made as small as possible to cut to a minimum the wasteof combustible mixture at this point.

The valve 88 permits the use of a low pressure in the pressure chamber I30 as this valve does not open until the pressure in the cylinder drops below that in the pressurechamber, thereby permitting a high degree of scavenging and a more efllcient over-all performance.

A flange I30 is secured to the flywheel to provide a place for theusual starting rope I52.

Thus it will be seen I have provided an efllclent gasoline engine of the two-stroke cycle type which has splash lubrication and is economical to build.

While I have shown and described but a few embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, may be made which do not depart from the spirit and scope of my invention as disclosed in the appended claims.

I claim as my invention:

1. In a two-cycle internal combustion engine, a cylinder, 9. piston slidable therein, a crank-case, a crank shaft, a connectingrod operably connecting the piston to the crank shaft, inlet and exhaust ports in the sides of the cylinder uncovered by the piston only at the bottom of its stroke, a compression chamber, means operable by the crank shaft for compressing'air in the compression chamber, an inlet passage connecting the compression chamber with the inlet port, a valve in said passage operable by the relative pressures in the cylinder and in the compression chamber for closing the passage between the compression chamber and the inlet port just prior to uncovering-the exhaust port and for opening said valve after the pressure in the cylinder has dropped below the pressure in the compression chamber, and means for carburetting the air supplied to the inlet port.

2. The engine according to claim 1 in which the last-mentioned means for carburetting the air is located in said inlet passage between the compression chamber and said valve.

3. The engine according to claim 1 in which said carburetting. means is a pressure carburettor.

JAMES H. ROTHENBERGER.

REFERENCES CITED The following references are of record in the file of this patent: A

UNITED STATES PATENTS 

